Application of metal sulfide catalysts in the vapor phase treatment of mineral oils



Patented Jan. 28, 1947` .UNITED STATES PATE-1N `MPL10.'rrroN oFME'rAL [suprime` CATA; l y Lvs'rs IN THE VAPOR PHasETaEArlvrnNrm f -oFMrNEltALoILs "zen'e v." Jasaitis, :Lbs Angelesglanaunonala in Davidson, Long Beach,` Calif.,`ass`ignors.to Shell Development CompanyySan `Francisco;Calif, l alcorporationof Delaware x,

' No Drafting. puede Noventa e, may

Serial No. 627,095

This invention relates Vto the application` of solid hydrogenationfdehydrogenation catalysts containing as thepredorninant active constituent l i sciimsf. (01.196-24) t one or more `metal suldes. More particularly the invention relates toanimproved method "for the application of such catalystsv for the treat-j@ ment of mineral oilssuch'asthe various distillates obtained from petroleum, 011 shale andthe pnydrog" genation of coal and tar. Two of the most important classes of hydrogenation-dehydrogenation catalysts arethe suldes and oxides of metals. Theseftwo classes of catalystnd wide application .inthe treatment,

`becoming'relativelyinefficient ln the dehydro;

genationprocessstill have an appreclablehydrof-.,

genatlon` abilityvand consequently 4it has been proposed to utilize such `catalysts forthe desul-` l furizationofloils after theylhave lost eiciencyin t dehydrogenation and before regenerating them."A

This allows thecatalyst to be usefully employed overa longer period of time before the plant must.; y be shut down tolallowgnforcatalyst regeneration.

However, the desulfurizing` action of Such spent l afresh` catalyst; 1f

of mineral oils due largely to thegfact that` they"` are not poisoned by small amounts of `sulfurcompounds normally "foundfin such products(V ",'Ihese` two classes f catalysts areA both used under low temperature conditions to hydrogenate unsat-` urated materials and sulfurcompounds. Insuch" use they are insensitive tobsulfur compounds "in thefeed and retain their efficiencies overconsiderable periods oi continuous operation. In most cases, howe ver, it isdesirable to operate at `higher temperatures whensubstantial` dehydrogenation and/or dehydrocyclization takes` p1ace",`j""since under such conditions'a `large `consumption of costlyl hydrogen is avoided and products of 'superior solvent properties and/or `antifknock pro`p` erties are obtained; (duefto an appreciable con-1 version of non-aromatic hydrocarboncompounds in the feed to aromatichydrocarbons). In this latter application these twotclasses offV catalysts are not equivalent. `The oxidecatalysts .quickly` lose their.eectivenessdueto accumulation of"4 carbonaceous `deposits and must be frequently The object `of the' present invention is to provide a method whereby metal sulfide hydrogenationedehydrogenation catalystslmay ,be usefully l i employed a greater percentagepffthetime and to betteradvantage, `An;` objectfof the invention is to provide a method ;of application of suchU catalysts wherein the percentage of time spent ln regeneration of the catalyst isless-` Anotherq f objectloigthe `inventionjis to Vprovide a methode;

of `applicationof such catalysts wherein the max? imum desulfurizingact'ivity of these catalystslisl utilizedto advantage.Y f

These and other objectsyare attained em-` ploying` such catalysts inthe following repeated 1 sequence` of process steps. l 1

1l,v Dehydrogenation of a relativelysulfur-freey mineral foil., to" obtain :an appreciable increase in l aromatic content of #said oil..

2. Removingjof carbonaceousldeposits from the,

catalystfby burning. y t Y l l 3. Desulfurizationtof a `relatively sulfur-rich mineraloil under hydrogenation conditions. y

regenerated. When using such catalysts,"there l fore, the plantand reactors arespeciallydesigned` for eilicient and rapid regeneration, and" regener-` ation of the `catalyst is an integral part'of `the process.

The sulfide catalysts, onithe otherhandlusu-1 ally become deactivated at a muchfslowerf rate@ Also` the regenerationof theV suldecatalysts is generally al-rather complicated `and `time-consuming procedure.

rule Warrant the inclusion of elaboratelregeneration facilities as a part of the plant.V Thus,` the catalyst is often used until itis spent ,and then replaced by fresh catalyst. -Thespent catalyst".

canusua-lly .be regeneratedin situ, l;iul; .this;re-4 quires taking days. im `It is knownV that these sulfide `catalysts,` afterI Consequently regeneration of the sulfide catalyst is carried outonly atyrela. tively infrequent periods and this does not-as a`j the plant off4 stream for several .convertedln thegvaporwphase and, in the.` pres-"f ence 'of hydrogenfwith the ald of; a metal sulfide catalyst.; Therefore, "it amai/abe applied,.with a; variety of `mineral `oils `under `a variety ofconv ditionsland witha variety of metal sulfide; cataf lysts.` It. f is` particularly advantageous `however` where thc-ru catalyst contains `as the predominat-l` ingactiveconstituent'a` sulfide of a molybdenum,`

The `process `of the` invention is of" general` application in` suchcases where a mineral oil is tungsten,` iron, cobalt orynickel `or a mixture thereof, and `particularly `where the catalyst consists essentially oi one or more of these constitl uents, i.' e..it is not a supported typelcatalyst `consisting largelyof arcarrienmaterial.

In theffirstfof the abovafspeeedA repeated Se;

l quence of steps the catalyst is usedunderdenydrogenation conditions for@ the dehydrogenationI of arelatively sulfur-free mineral oil, jlnorderj, l to havefdehydrogenation conditions the temper.-li` ature must be abovegabout 800 Rand ispreferv-fr catalysts is not nearly as complete. as whengusng 1000 p. s. i. The sulfur content of the feed'used in the first step should be below 0.1% and preferably on the order of 0.01 to 0.05%. Under .these conditions the process is carried out continuously for a considerable time, for example 200-1000 hours or more. During this period the activity of the catalyst gradually declines.

When the catalyst has declined in activity to the extent that the desired dehydrogenation is no longer obtained the first process step is concluded. At this point the temperature could be lowered to 800 F. or below and a high sulfur feed treated. However, such operation does not give optimum desulfurization and does not utilize the catalyst to the optimum advantage. Therefore, the catalyst is subjected'to an incomplete regeneration treatment which comprises burning off carbonaceous deposits under controlled condiltions. yThis regeneration treatmentmaybe carried out with air or with air diluted with nitrogen y or flue gas, but is preferably carried outusing a mixture of air and steam. This treatment re-A moves the bulk of the carbonaceous deposits without material loss of strength of the catalyst particles.

The catalyst at the conclusion of this second step is not regenerated vin the sense thatvit has its original activity and is totally unsuited for continuation of 'step l. Thus, if it is used again as in step 1 it is found that the activity for de-f hydrogenation is only about '70% of that of the fresh catalyst. Moreover, if the catalyst'is first reduced the catalyst particles lose strength and many of them crumble to dust which plugs the catalyst bed. It is found, fhoweverythat the catalyst after the burning step is exceptionallyy active for effecting hydrogenation of sulfur cornpounds.

mineral oil is treated with the catalyst under hydrogenation conditions following the burning treatmentexcellent desulfurization is effected without appreciable loss of strength of the catalyst particles due to reduction. Also, it is found that after employing the catalyst in this manner for a time it becomes substantially completely regenerated for the dehydrogenation of step 1. Consequently, after removing carbonaceous deposits from the catalyst by oxidation in step 2, the catalyst is immediately used in the third step of the process forthe treatment of a high sulfur mineral oil under hydrogenation conditions. The temperature shouldbe below 800 F. and preferably between about 400 F. and 800 F. The mol ratio of hydrogen to hydrocarbon is preferably above 3. The total pressure may vary over a very wide range-but is preferably between about 400 and 1000 p. s. i. The mineral oil should contain at least 3% sulfur. Under these'conditions the process may be carried out continuously for a considerable period while obtaining substantially complete desulfurization.

At the oonclusionof step 3 the conditions are changed to dehydrogenation conditions. The low sulfur feed is substituted for the high sulfur feed and the cycle of steps is repeated until such time that the catalyst becomes permanently im- {paired to such an extent that its replacement is advisable.

Also, it is found that if a high sulfur- An application of the process of the invention is illustrated by the following example:

The catalyst consists of pellets of a mixture of about two mols of nickel sulfide and about one mol of tungsten sulfide, `the nickel sulfide being the major constituent on a mol basis. This catalyst is employed for the dehydrogenation of a fraction of petroleum rich in methylcyclohexane and relatively sulfur free (less than 0.10% sulfur). In this first step the catalyst is used continuously at a temperature between about 800 F. and 900 F. vunder a pressure of between about 500 and 800 p..s. i. and with about 7 lmols of 'recycled hydrogen'per mol of hydrocarbon feed. When the efficiency of the catalyst, as measured in terms of percent available methylcyclohexane dehydrogenated, has fallen the process is stopped and the catalyst is subjected to an air-plus-steam treatment under the following conditions:

Steam flow vapor space velocity 60 F.

per minute Air flow vapor space velocity-,60 F. per minute e 2-15 Inlet oxygen concentration, v Y 1*-10 Temperature F. inlet 860-8'15 Temperature F. maximum hot zone-- 1090-1115 Temperature F. average ht`zone 910-1060 Reactor exit pressure p. s. i. g ..-.a 0

The catalyst without further treatment is then used for the catalytic,desulfurization ofr a high sulfur' petroleum fraction `(15.6% sulfur) at a temperature between about '100 F. and 800 F. at a pressure between about'500 and 800 p. s. i. and with about 'l mols recycled hydrogen per mol of hydrocarbon feed. The desulfurization is essentially complete. After a period the temperature is raised and the relatively sulfur-free petroleum fraction is treated as described.

The dehydrogenation efliciency after returning to the first step of the cycle is found to be substantially equal to that ofthe fresh catalyst. Ifon the other hand, the catalyst is reduced with hydrogen atV the end of the air-plus-steam oxidation step the catalyst pellets tend to crumble and about 25% fnes is produced. The dehydrogenation activity of the catalyst is only about 68% of that of the fresh catalyst.

As pointed out7 above, the catalyst, if reduced after the` air-plus-'steam oxidation, tends to lose strength and crumble... In order to minimize the danger of reduction during the third step of the process the sulfur content of the feed used vin this step should' be at least 3. Also, in order to minimize thev danger of disintegration of vthe catalyst pellets due to a possible loss of strength it is desirable to pass' the reactant vapors up through the catalyst bed in the third step. The processing in step 1 however may be carried out with the reactant vapors passing down through the catalyst bed;

In the above-described method of the invention the catalyst is lusefully employed all of the time except for the relatively short time that is required to effect the oxidation in step 2. Also,

ing steps :V (l) dehydrogenation at a temperature above about 800 F. of a relatively sulfur-free mineral oil containing less than.0.10% sulfur to obtain an appreciable increase inaromatic content of said oil; (2) removing carbonaceous deposits from the catalyst by burning; (3) desulfurization of a. relatively sulfur-rich mineral oil containing` at least 3% sulfur under hydrogenation conditions at atemperature below about 800 F.y

2. Process according toclaim 1 in which the metal sulfide catalyst lcontains as the predom inating active constituent a suliide of nickel.

3. Process according to claim 1 in which the metal sulfide catalyst contains as the predominating activev constituent a sulfide of cobalt.

4. Process according to claim 1 in which the metal sulfide catalyst contains as the predominating active constituent a major mol amount of a sulfide of nickel in combination with a minor mol amount of a sulfide of tungsten.

5. Process according to claim 1 in which the l 

